1. Field of the Invention
The present invention relates to a multi-functional composite apparatus, for example, connected to a network including computers, a control method thereof, and a network system therewith.
2. Related Background Art
An example of formation of the network using computers is the network of hierarchical star topology (connection configuration) as shown in FIG. 1. For forming the hierarchical star topology (connection configuration), each wire 101 is connected between host computer system 102 (hereinafter referred to as PC 102) and hub 103, between PC 102 and node 104, or between hub 103 and node 104. In this case, the PC 102 is provided for control of the network and the network includes only one PC. The hubs 103 having a repeater function of signal provide connection points of additional nodes 104 or hubs 103 and are thus indispensable components for establishing the network. Each node 104 is a computer I/O device, for example, such as a printer 106, a scanner 107, or a keyboard (not illustrated).
In order to realize the plug and play function (hereinafter abbreviated as PnP function) in which the host system recognizes a device connected on the above-stated network, finds a driver for control suitable for the device, and installs it at appropriate timing, there is a conventional method for reading information about the device (node 104) connected, in accordance with a protocol preliminarily determined. Specific examples of this information include a name of model, a name of manufacturer, power consumption, a maximum data rate, and so on.
For actualizing the PnP function by OS having limited program capacity, there is a method for moderately classifying the devices (into a printer class, an input class, a display class, an image class, a sound class, etc.), based on the information about the devices (nodes 104), and driving each device by a standard driver for its corresponding class. For example, the standards including IEEE1394 and USB are known as standards for the network to realize the PnP function stated above.
In recent years, the demand is increasing for composite apparatus having a plurality of functions (of different classes), e.g. a printer and a scanner. The method by the PnP function stated above is, however, not ready for composite equipment as a combination of devices of different classes, because it is adapted for reading the information only once upon recognition of device. Since the method is ready for only single-function devices, the following problems will be posed if the composite apparatus is connected through one network interface.
A plurality of drivers, each having a single function, are not allowed to be assigned to one network device. Namely, the PC does not allow a plurality of drivers to be installed for one network device.
Since the composite apparatus is off the standard concepts for the classes, the devices thereof are unable to be driven by the standard drivers.
This requires a special driver to be prepared for the devices. It is thus necessary to prepare one new driver by combining individual drivers used heretofore.
Since a plurality of mutually different drivers, e.g. drivers of different concepts such as the printer and the scanner, are combined into one, the resultant program must be larger than the drivers of single functions.
When one driver is adapted for two functions, e.g. the printer and the scanner, the system resources will be taken up more than necessary. Simply speaking, they are double those for the single-function devices. It is thus naturally concluded that this method fails to take full advantage of the features of the PnP.